1. Field of the Invention
The present invention relates to a raise in reliability of a multilayer wiring structure, and in particular, to a stress analysis method, a wiring structure design method, a program, and a semiconductor device production method.
2. Description of the Related Art
Recently, achievement of lower resistance of wiring resistance, lower dielectric constant of an inter-layer insulating film, etc. are advanced for acceleration of semiconductor devices including LSIs. For example, a material of wiring has transferred to copper (Cu) from aluminum (AL). In addition, low dielectric constant films (low-k films) including a simple silicon oxide film (SiO2 film), an SiO2 film in which fluorine is doped, and an SiO2 film including an organic component have been employed also as an inter-layer insulating film.
A low dielectric constant film is formed by reducing the density of its material, eliminating the polarity in its material, or the like. For example, in order to decrease the density of material, generally the material is made to be porous. Since having a low film density, generally a low dielectric constant film has low mechanical physical property values such as a Young's modulus. That is, a low dielectric constant film has low strength in its material itself.
Furthermore, since a low dielectric constant film has a film structure with low polarity in order to decrease a dielectric constant in the film, the adhesion strength between low dielectric constant films or in a stacked layer interface in a stacked film of a low dielectric constant film and another film is low. For this reason, a material of low dielectric constant film deteriorates easily by, for example, penetration of a gas used when processing a via hole, a trench for wiring, or the like in the low dielectric constant film, or production processes.
As described above, a semiconductor device using a low dielectric constant film has a possibility that the mechanical strength of a material of low dielectric constant film itself deteriorates, or the adhesion strength in the interface of a stacked film including the low dielectric constant film deteriorates.
The weak film strength of such a low dielectric constant film and in particular the weak adhesion strength in the interface of a stacked film including a low dielectric constant film have been a serious obstruction in the multilayering process which forms wiring of a semiconductor device in a multi-layer structure. In order to conquer this obstruction, enhancement in reliability is achieved by arranging dummy wiring as reinforcement in a low dielectric constant film (for example, refer to Japanese Patent Laid-Open No. 2003-167929).
A method of determining a form and an arrangement position of dummy wiring is known by a stress analysis using a computer as one of arrangement methods of dummy wiring. The method of dummy metal arrangement using a stress analysis performs the stress analysis in a local portion such as a vicinity of one via, or a vicinity of one pad, and arranges a dummy form according to the result of the stress analysis over a whole chip.
Here, in view of a whole chip, inside of the chip, various regions where the wiring coverage values and wiring forms are different, such as a high density pattern with a high wiring coverage, isolated wiring, or a space section in which a pattern does not exist, are arranged on the basis of a wiring design of the chip. In a boundary section between regions in which the wiring coverage and wiring forms are different, that is, a boundary between different patterns, or a boundary section between a pattern and a space, stress concentration resulting from a design of pattern arrangement is generated. For this reason, defects such as delamination and a crack in a pattern boundary section may be caused.
Nevertheless, in a conventional local stress analysis, it is not possible to derive an analysis result of the stress concentration resulting from a pattern arrangement design by chip. In addition, when faithfully modeling a whole chip up to one via on the basis of the conventional stress analysis method, the total mesh number becomes tens of billions of order, and requires huge computation time.
As described above, in conventional arrangement methods of dummy wiring, since the local stress analysis is performed, it is not possible to perform efficiently an analysis in consideration of stress resulting from a pattern arrangements design of a whole chip. Therefore, since it is not possible to achieve effective dummy arrangement, there is an extremely high possibility that a fatal defect may arise in a pattern boundary section in a heat process and processes, where an external force is applied, such as bonding, and probing. Hence, there is an extremely high possibility that a fatal malfunction may arise in a semiconductor device and its production process. That is, there is a possibility that the performance, quality, and the like of semiconductor devices may deteriorate and the reliability of semiconductor devices may drop. In turn, there is a possibility that faulty semiconductor devices may be produced, a yield of semiconductor devices may drop, and productive efficiency of semiconductor devices may drop.